ULX doesn't have/allow non-admins to noclip unless they use the "ulx noclip" command.
If you have UClip, another addon made by Megiddo, (not part of ULX), then remove it for spacebuild2.
If not;
1) Some other mod is causing this.
2) you've somehow edited your groups to allow users to have 'ulx noclip' access,
3) you have a much larger problem where you've given admin access to all your players.
Even if reasons two or three I gave were somehow true, they would all have to type console 'ulx noclip' or chat "!noclip" individually to get noclip access if sbox_noclip 0 were set.