Thanks for the inputs, actually I hate Anet A6 printer, specially it's head, because it jams a lot also changing the filament is a pain in the ass, I should unscrew some screws to make it a bit loose so I can finally put the new filament into it. 
Yes the Anet extruder isn't the nicest - the lack of a thumb tab on the lever arm to push the v-groove pressure bearing away from the extruder drive gear will make it difficult to manually load/unload filament. My CTC plastic bodied extruder is even worse - no lever arm and no spring and screw to adjust the 'nip', which you have to set by slackening the mounting screws and nudging the extruder body sideways!
Be careful loosening screws - the arm pivot and pressure bearing screws must be kept tight as any slop in the arm or bearing will cause inconsistent extrusion and even jams. The tension screw is fair game - it only needs enough pressure to grip the filament enough to turn the motor if you pull on it with the power off, or steppers inactive.
You could upgrade the extruder drive assembly to one with a thumb tab, (though check clearances at the X travel extremes before buying, or you could use G-code for filament load/unload, which I find to be very reliable unless I am impatient and fail to properly preheat the hotend before doing a filament change. If the end of the filament has bulged due to heat creep and extrusion pressure it can be impossible to retract past the top of the heat-break or through the extruder drive, even with the pressure arm fully held down. At that point, if you haven't totally jammed or broken the filament by tugging on it, the easiest way to clear the jam is to unscrew the nozzle and feed the filament till you can cut it below the hot block. If the filament is broken, or jammed in the heat-break throat or extruder frame you'll probably have to strip down the extruder to clear it.
Here's what I use in Marlin 1.1.x config file user command format:
#define USER_DESC_3 "Load Filament"
#define USER_GCODE_3 "M83\nG0 E5 F5\nM0 Fil. gripped?\nG0 E50 F300\nG0 E10 F50\nG0 E-1 F50" //extruder relative >creep 5mm to engage > pause > fast load 50mm > purge 10mm > retract 1mm
#define USER_DESC_4 "Eject Filament"
#define USER_GCODE_4 "M83\nG0 E40 F200\nG0 E-60 F3000\nG0 E0 F50\nM104 S0" //extruder relative > ram > v. fast retract, cancel F3000 > cooldown
and translated back into commented plain G-code:
Load FilamentM83 ;extruder relative
G0 E5 F5 ;creep 5mm to engage
M0 Fil. gripped? ;pause
G0 E50 F300 ;fast load 50mm
G0 E10 F50 ;purge 10mm
G0 E-1 F50 ;retract 1mm
Feed the filament into the extruder with gentle pressure and trigger the macro (or visa-versa). It creeps the extruder for a minute to grip the filament then asks you if its gripped.
Confirm and it completes loading the filament. If its not gripped, reset to abort, re-enable the hotend heater and try again. If the distance from your extruder gear to the nozzle isn't 50mm change the fast load line to match.
Eject FilamentM83 ;extruder relative
G0 E40 F200 ;ram
G0 E-60 F3000 ;v. fast retract
G0 E0 F50 ;cancel F3000
M104 S0 ;cooldown
The ram sequence requires the nozzle to be fully up to temperature or even 10 degrees hotter than your usual printing temperature. The E40 in the command is the length in mm of possibly heat affected filament to be purged, you may need to use E50. On the next line it fast retracts -60 mm which is normally enough for the filament to clear my extruder drive gear. You shouldn't increase this too much as if it jams on retract a longer movement will grind through the filament and force you to do a full strip-down.
Note that Marlin (and most other firmwares) have max speed limits for motion, so the F3000 fast retract probably wont actually retract at that speed. It will retract at the lesser of the extruder's max speed or 3 m/minute.
Ideally you'd recompile the firmware to enable these user commands, or you can send the gcode from your PC or save it to the printer's SD card as two files so you can run them from the printer control panel.
Nozzle blockages are best cleared by doing a cold pull. If you have difficulty doing one in situ, it can be done off the printer - secure the nozzle in a paperclip with a M6 nut, clamp the paperclip sideways in a metal jawed bench vice with the nozzle facing away from you, then heat it with a lighter flame on the nozzle not the nut while pressing an offcut of filament into it till you get extrusion or backflow. Allow to fully cool then pull the filament steadily (but not so hard it breaks), and heat the nozzle with the lighter flame till the filament comes free. Done right, you can see right through the nozzle orifice afterwards.
If you prefer to poke a wire up the hot nozzle, use a copper wire, stretched for stiffness rather than a steel wire or needle, as its important not to scratch or enlarge the orifice.