How can delete a user without deleting the post and comments in wordpress?

1. Login as Administrator (must be not login to whom you are going to delete).
2. Go to User Listing.
3. Click on check box in front of user to whom you want to delete. See below screenshot.

4. Click on delete icon. It will bring to you new page.
5. Now assign all post to another user/administrator. See below Screenshot.

6. Click on "Confirm Deletion". User deleted successfully.