Help Please....Deck post question
Decks have been under serious scrutiny for years because of collapses involving injuries, yours was obviously not done under permit as it should have been. The post require footers to below the frost line, check local code for that number. And the only way to do it is install temporary support while the post is removed or at least moved so you can dig out under.
While you are at it, check how the ledger is connected to the house. VERY important on a deck off the second floor. The number and size of bolts varies according to code, but I always think more is better.