When closing a cc is it recommended to transfer the line of credit if you don’t particularly need it, or can too much credit line can be detrimental to future openings?
You move the credit line because a reduction in credit line will ding your credit score temporarily.
But financial institutions have an upper limit to the amount of credit they think you can carry. So if you have too much available credit, even if you're not using it, they won't extend more credit - making it harder to open new cards.
One way around that is to call reconsideration and ask to move existing credit onto the new card you want to open.