This is a duplicate of a question I put on Super User. But it may get answered here:
It was easy in Sublime text 2, but how do I remove (or limit the number) of code syntax files accessible on the bottom right hand corner.
For example put Pascal into a folder when it's backed up, but not used.
You can add packages to your ignored_packages user preference, and Sublime Text will ignore everything in those packages - including syntax definitions. There's no need to do any folder manipulations or backing up.
For example, to remove the Pascal syntax from the list:
// List any packages to ignore here. When removing entries from this list,
// a restart may be required if the package contains plugins.
"ignored_packages": ["Vintage", "Pascal"]