My suggestion:
If there's anything on the drive, BACK IT UP (going further will erase the data).
Then...
Boot to INTERNET recovery (NOT "the recovery partition")
Command-OPTION-R at boot.
You'll need your wifi password (if you're connecting via wifi).
The internet utilities take a while to load (be patient).
Then...
Open disk utility.
Go to the "view" menu and choose "show all devices" (IMPORTANT STEP)
Now, ERASE the ENTIRE drive. APFS with GUID partition format.
When done, try to repartition the drive now...