Then you want to erase the storage on your NUCs, there are some options.

Specialized tools:

• DBAN free edition doesn't support EUFI, so it can be a pain to use
• Use an external USB mSATA SSD enclosure to connect to your workstation and erase it
• Specialized paid tools

Medium effort:

• Boot to Ubuntu Live CD (https://help.ubuntu.com/community/LiveCdRecovery)
  • reformat partitions
  • remove partitions (just removing without formatting leaves the data still recoverable!)

Easy:

• Looking for suggestions