Hello there,
There are various ways for you to address this situation. If you want to do this for a few users, you can use frx command tool with the migrate-vhd modifier and you can find more information here. Another alternative is by using diskpart and the instructions on how to do it are here.
My storage is running out of space because of FSLogix! https://techcommunity.microsoft.com/t5/fslogix-blog/my-storage-is-running-out-of-space-because-of-fslogix/ba-p/1333170
Hope this resolves your Query !!
--If the reply is helpful, please Upvote and Accept it as an answer--