By default WordPress allows your blog post authors to delete their post by clicking the delete button from publish metabox or from all post list. If you don’t want to allow this post delete option in your WordPress site then you can easily disable it by using a simple WordPress plugin called Disable Delete Post or Page.
Install and activate it. After activation it automatically removes Delete link from following 2 admin area places:
- All Posts List or All Pages List
- On Edit Post Page using the Publish meta box.