Remove the appropriate folders from addons, then remove the ulx/ulib folders from garrysmod/data.
ULib (if none of your other addons use it)
<gmod>/addons/ULib
<gmod>/data/Ulib
ULX
<gmod>/addons/ulx
<gmod>/data/ulx
We hate to see you go! If there's anything we can do to improve please let us know.