Legal Question in Real Estate Law in Illinois

Possibly. Removing you from the mortgage may be his way of saying he thinks he can get a new mortgage loan on the property by himself that will pay off the existing one. Lenders typically want all the owners to sign a mortgage so that may not happen if you refuse. But if you and he own the property in "joint tenancy" and he signs a deed attempting to change that, he could wind up in a position where he might be able to get a lender to lend against just his "half" and you could wind up with a stranger as a co-owner with you if he defaults on his loan. There are other ramifications.