My thought is that "When you see something as issue you never find a solution or probable solution. When you see that as a learning experience you will always get something at the end".

To make history of main branch as clean as possible and protect the branch , Admin has created following policy settings for merge.

Now the project I am working I have to merge one branch to another branch without loosing the history of source branch. This is not allowed due to branch policy as you can see following things.

Solution:

You can set following things at repository level to set permission for User group or user.

Double click on "not set" . It will toggle different option Allow, Deny and Not Set. Choose "Allow".

After that you can see following things. ( Refresh of pull request page required). You can see "Must override policies". On Selection of this you can have reason box . Provide that and complete the PR (pull request).