File Share Encryption

I recently inhereted a handful of MS Surface tablets, and they all have Desktop Encryption. I've been hired by a company to take over their IT, and this is one area I've never played in. The tablets work fine as is, however, one of them needs to have the OS reinstalled. I know th password to get past the desktop encyption screen at bootup, but I can't figure out how to remove it completely.

The domain server from the previous company is gone, so I no longer have access to that. I was able to remove the devices from the domain, and am using the Administrator/local accounts. 

Where do I go from here? If the other IT company won't play nicely, is this one a brick?

Thanks!

Can you use the recovery images from Microsoft to recover? Do you have an imaging solution with any images for the Surface? Imaging a Surface requires some unique steps so you don't brick the machine. Same goes for encrypting them with something other than Bitclocker. The MS recovery images may be your best bet to start.

https://www.microsoft.com/surface/en-us/support/warranty-service-and-recovery/downloadablerecoveryimage

I have Surface 3 and 4s in my environment and have gone through a lot of effort to get them to play nice. I'm happy to share any notes/experience I have.

Todd