So your first common ancestors are your great great grandparents, so that's third cousin, and they're a generation older than you, so once removed. Third cousin once removed.
I believe that the answer is second cousin once removed.
I believe you need to count the distance to the common ancestor from the older generation of the two people being related.
I agree that the first common ancestor is OP's great-great-grandparent. But only OP's relation's great-grandparent. So OP's parent and OP's relation are second cousins.
Then the removed takes you down the tree from OP's parent to OP.
Who's gonna tell him?
— https://en.wikipedia.org/wiki/Naming_of_the_Americas