Techinical Pro HB1502U rack mount amplifier How do I remove connectors to board

[onedumbquestion]

I'm having trouble removing connectors from the board and also it seems to be missing a bracket to hold the front 1/4" jacks panel on so my questions are what's the missing part, I guess after I remove the board I'll find it underneath, and as you can see in the photo I pried up a connector and the nylon rose up leaving the pins exposed What's the right way disconnect those kind of connectors?
https://imgur.com/a/8msXj0D
https://imgur.com/a/YFeYi3h