Will deleting a device from iCloud remove data from that device?
Removing the phone from your iCloud 'find my' structure won't in itself remove any data from the phone…
…but re-assigning it to a new owner will. It will have to be set up again from scratch.

As the phone is currently owned by your Apple ID, so are all the apps &amp; the data stored within them. You can restore [most of] the apps, music etc if you set up Family Sharing but any data in those apps will not be transferred with them, as it still belongs to you.