Where do I enter wash sale loss disallowed in Summary Investment Sales Section? (not entering individual sales) Do I use Adjustment to cost basis?

Yes, you enter the wash sale as an Adjustment.  After entering the summary totals, check the box for "I need to adjust my total cost basis".  Enter the amount of the Wash Sale Adjustment, and mark the box W, (nondeductible loss from a wash sale).

@DavidD66 

your answer is incorrect. 

poster want to use the summary method.

@cjwclw 

after entering the basic summary, it ask you if you have any adjustments (or other).

Say YES and the box for total  adjustments should appear.

Is wash sale adjustment available in Deluxe desktop version?

Yes it is. See here

Further up on this page, you will checkmark I need to adjust my total cost basis