Which section are you trying to remove,I'm guessing the corner return jamb??
I've been in the industry a long time and it is usually difficult/impossible to match someone else's extrusion to another.
Rivets are used to hold sections together.
They should be visible on a sliding screen.
The headrail of a slider, depending on the brand, can have a lift off capping section which, once removed, will show the main sliding track. This is usually rivetted to the corner return jamb and the wall jamb.
As you have noted, if you post some pictures it will help.
Good luck