I don't know how well u can get the just of the deck from the pic (posting from a phone) but I have a 1 level 2 size deck (1 sec 16x30 and the other 10x24). The deck is at second floor level, but the way the backyard slopes, the support beams are 89in at its tallest and 51in the lowest part of the deck/post. In the smallest part of the deck, I wound not have to excavate, just grade and pave, but I need to excavate to remainder to get it at a minimum of say 76-76in.

The footings for the deck are all 12x48 poured concrete tubes.

How much can i safely excavate ans not weaken supports?

At the widest part (16x30), the tallest support beam is 72in, the the shortest of 51in previously mentioned. So I'd b excavating at most about 2 ft down.

Since the widest part of the deck is the one that needs the most soil removed, if I excavate say 10-12ft of the 16ft, leaving 4-6ft nearest the footings intact, would the deck still b appropriately supported?

Any suggestions/things I should consider?