uninstall .3gx files

[ut2ten]

how do you uninstall some .g3x files that i've downloaded.. coz i get an error message at the bottom of the screen when i select other aircraft even thought it wasn't the aircraft i selected..also when i import some of these file a pop up will say if it will overwrite some file or not install..if i overwrite does that change the original
.g3x file or aircraft(heli) on the RF 3.5 files.. i notice Heli Max Cp has become Heli Max Cp 450xl after installing trex450xl.g3x file..the trex was not in the custom aricraft folder..want to get the original back hence the question -how to uninstall .g3x files..

thanks in advance..