Your position isn't clear. The first 4 option positions listed are a pair of short horizontal spreads, not diagonals.
A diagonal spread involves a long and short position in two options of the same type (two puts or two calls) with different strike prices and different expiration dates.
If you combine a diagonal call spread with a diagonal put spread then it's a double diagonal spread which is effectively buying a longer term straddle and selling one shorter-term strangle (or vice versa), which you have not done. Buying a double diagonal means buying the far dated expiration not the near dated one.
Your last 4 positions are all short positions so I don't know what to make of them. They're not spreads.
You can close legs individually but if you want to close both sides of a spread, a spread order is a more effective way of doing so.
The OCC will automatically assign options that that expire ITM unless the owner of the long options designates that they not be exercised.