In VFP DELETE and UPDATE statements are much more limited than SELECT. Also, I don't see where 'xpat' table comes from.
Try this way

Delete pattern From pattern ;
		JOIN CurRemove ON CurRemove.patid = pattern.patid ;
		LEFT JOIN CurExcept ON CurExcept.patid = pattern.patid ;
	WHERE CurExcept.patid IS NULL

> Anyone have any idea why the following code would be throwing a "Too Complex" error.
>
>

>Delete From pattern ;
>Where pattern.patid In (Select CurRemove.patid From CurRemove) ;
>.and. xpat.patid Not In (Select CurExcept.patid From CurExcept)
>