That plug should not require an Allen wrench to remove it. Your 3/8" drive ratchet wrench should fit that plug perfectly.
3/8 inch Allen wrench.
You need a 3/8 Allen Wrench
It takes a FA12A Allen wrench.
3/8" Allen wrench.
That is a 3/8 Allen.
A 3/8 Allen key.
Depending where it was built, a 3/8 Allen key or 15 mm regular wrench.
3/8
It should be a 3/8" Allen wrench.
I believe that's a 3/8 Allen wrench.
A 3/8" Allen wrench.
3/8"