selling a single wide in mobile park

(White City Oregon)

I bought a single wide in a park. I now want to put it up for sell. Other single wides in park have been sold recently. The new management said I can't sell it. I would have to move it.Said they want nothning but double wides in furture in said park. The lot is not large enough to substain a double wide. Is this legal, comsidering others have recently sold?