If your theme or plugin no longer needs TGM Plugin Activation (TGMPA) support, then these are the steps you need to take to remove TGMPA. Some initiative may be needed depending on how the theme or plugin author has added it in, and it is assumed you are comfortable editing PHP files / FTP as needed.
tgmpa_registerin your theme or plugin (other than the TGMPA class file), so search for that. The registration function may be with other code in
init.phpor a separate file such as
include/tgmpa.phpor other file.
require_once()call that references the TGMPA class file: The file name is almost certainly unique, so search your theme or plugin for that. The theme or plugin author may have used
require_once, and they may have added extra
( )around the file path.
class-tgm-plugin-activation.phpfile (or equivalent if renamed) can be deleted from your theme or plugin.
With the plugins registration, the class file reference, and the class file itself all removed, your theme or plugin will no longer be using TGMPA.