mr64bit_SoapDM automatically unloads all the stock plugins when the game starts, then reloads them when it's done. You can change what gets loaded/unload in cfg/sourcemod/soap_live.cfg and cfg/sourcemod/soap_notlive.cfg. (they're just cfgs that get exec'd, so you can put other stuff in there if you want)
This. Just remove
sm plugins unload adminmenu
sm plugins unload basecommands
from cfg/sourcemod/soap_live.cfg.
adminmenu handles the admin menu itself, and all functions present through the admin menu. basecommands handles those same commands from the command line (cvar changing, kicking, map changing - only for admins). You don't need to keep basecommands loaded if you only use the in-game admin menu, though, since it isn't a dependency.