I answered an OP’s question some time ago but the OP’s user account was removed and thereafter the points I earned were deducted. I believe that in this scenario the points should remain intact since the removal of an OP’s account is outside of my control and/or responsibility. Can there be a process to make this happen?
You do not directly lose reputation because you answered a question and the asker's account gets deleted. You only lose reputation in two cases: if the account that cast an upvote or an accept vote on your post gets deleted, or if your upvoted post gets deleted.
If the account that cast a vote is removed, the vote is removed. This helps limit vote inflation on old posts: to a small extent, it privileges content that remains relevant (and thus keeps getting upvotes) over the years. This is also necessary to prevent fraud: if orphan votes remained around, this would make it easy to create temporary accounts to upvote the same post multiple times or to upvote many posts of the same user without leaving traces.
If the post that deserves a vote is deleted, it's even more clear-cut. A user's reputation only depends on content that's actually on the site, not on content that was on the site in the past.
In both cases, there are exceptions, but the exceptions are just that: exceptions. In the normal case, you don't keep reputation conferred by a vote that is no longer present on the site.