Right click the folder and select Compact. This should remove them and should be part of your normal routine. Deleting a message marks it for deletion. Compacting removes it and frees up the disk space.

mags47 said

There is a whole page of them all with a line drawn thru them. How do I get rid. thank you

Thank you, I am probably not explaining it properly. When I delete my mail a line is drawn thru them but they do not move from my inbox. On my inbox page there are a load of deleted emails above my incoming mail and I have no idea how to get rid of them I am new to Mozilla

Does this apply to you? https://community.homestead.com/homestead/topics/when_i_delete_an_email_in_outlook_it_puts_a_line_strikethrough_through_the_text_and_it_wont_delete_the

Also right click the problem account in the left column and select Settings. Go to Server Settings What do you have selected for When I Delete a Message:

This is how it reacts when you have Mark as Deleted

You could try one of the other 2 options.

Thank you, you are a star. Have a good weekend.