View your repo's branches by selecting Repos > Branches while viewing your repo on the web.
Select the More options button at the end of the row of the branch you want to delete.
In the options menu, select Delete branch.
In the Delete branch dialog box, select Delete.
Visual Studio 2015 & 2017
Open up Team Explorer and go to the Branches view.
Locate the branch you want to delete. Remember that you can't delete a branch you're currently working in.
Right-click the branch name and select Delete. Visual Studio will ask if you're sure you want to delete the branch if you have unpublished changes.
You can delete a remote branch using the same method. Locate the tree for the remote in Team Explorer's Branches view (such as remotes/origin), right-click, and select Delete.
Delete a local branch using the git branch -d command while checked out to a different branch.
git branch -d <branch_name>
Deleting a remote branch requires use of the git push command using the --delete option.