Sir how do we disable header stats in admin. this is making admin very slow (see enclosed).

Clear/disable spam marking, as you have 250k that can be a lot for mysql table

Sir this does not answer my question. we have a lot of ads sir, All the count is making access to admin slow for my ads validation team.

Ok then you have to work on DB & tables optimization (index/reindex).
Simple count cannot be bottleneck.
Anyway if you choose to remove these from header, I recommend you to go into core and change header hook - so no function get hooked into header.