The short answer to this is: Yes, simply use the operating systems format command.
A longer answer would be to use a recovery key, certificate or password to access the files from the USB stick, copy them to a safe place on your computer and then format the USB drive.
I'm not aware of a decrypt option within FRMP, and I'm not sure there is a need for one.
Moved to the first choice for now for better support.
MWEBB is correct, assuming there is no issue occurring and you wish to just remove FRP Removable Media from the disk, there is no automated method to decrypt the disk. The way EERM works is by creating encrypted partitions on the disk and placing the files in the partitions. These partitions need to be removed and the simple method to perform such an action is to format the disk. The data stored in the partitions should be copied to another drive prior to formatting if it is wished to be retained and then copied back to the drive after the format is complete.
Thank you for your replies, I tried to create a new Encryption key(Recovery Key) from ePO but it is doesn't pull through. The new Encryption key doesn't show under "Available keys"
For now, I cannot format the USB until I get the data out of it first. I used the steps on the below link as a guide to create the key, please advise if there's anything missing?
I don't think you can retrospectively add an encryption key to an already encrypted usb stick, especially if you don't know the password or don't have the original key.
If it's encrypted using a personal key then you'll have to follow the instructions for making that key available to yourself. Going forward you might want to evaluate the use of keys within the organisation and perhaps use a Group Key. The instructions in the Product Guide give the example of a HR Key, that way anyone in HR can recover an encrypted usb stick that belongs to their department. It's a bit more admin but might be worthwhile and reduce the overall support when people forget their passwords or leave, handing in a stick that's encrypted with no means of accessing it.
I managed to recover the key. One major thing I did not put into consideration though was that, File and Removal media actually wipes the memory stick when encrypting it.
As Mwebb had suggested, I recovered the key and formatted the USB to decrypt it.
I think I need to go back to my Policies and review them.
Thank you all for your support.