Sofistik Reinforcement - can't make changes to reinforced slab dimensions

Hello,

I have problem regarding making changes on previously reinforced slab. I have reinforcement in a slab, and I have constrained all of the bars. When I try to make changes to the slab geometry and dimensions, it won’t let do it. I get this warning message. What should I do? Please refer to screeshots below. Thank you in advance!