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I wasn't aware simply being removed as an AU removes the account from counting in your credit history. Does it?
A maxed out cc would be a ding but unless you have several other cc maxed out it might be ok to leave it as is. If your overall credit is good, the removal of the TL may also be beneficial. The score simulator is a tool you can use to est what your score might be without the TL.
Also, in order for it to be removed from your CR's, you will need to contact the bureaus directly
Can you see what your AAoA is to see if it is indeed impacting your scores?