Double bed to single bed

I don't know of a super easy way. . But, if I were going to try it, I would get rid of the mattress on the double bed and work on re-sizing the frame. (Probably by selecting the outer vertices and moving them toward the center rather than resizing on the x axis to avoid deformation). Then clone a single bed, remove its frame, and import your resized double bed frame to replace it. Is there a particular bed you were thinking of?

That's just one option. Hopefully some other creators will chime in with their ideas, too