If you want to make sure your USB drives taken offsite can’t be used in another system to steel information you can encrypt them with bitlocker.
1. Open Disk Management
Hit start and type disk management and choose the result at the top
2. Find the drive that is plugged into the system but has no drive letter that represents your backup destination you have already configured.
3. Right click on the drive and choose “change drive letter and path” and assign it a drive letter not already in use.
4. Open Bitlocker Drive Encryption
Hit start and type Bitlocker and choose the top result on the top.
5. Hit “Turn on Bitlocker” next to the drive letter you created above
6. Select your choice for the locking encryption(I selected password) and hit next
7. This will begin the encryption, if the drive is blank it will be much faster than a drive that has data.