Backup run too slowly

Apologies but no, the download/upload time will be dependent on the resources available through your web host.

Can you tell me how to delete files was backup. I do not see any option to delete it !

You can delete a backup through FTP.

You can find more information on the Documentation site – https://docs.mainwp.com/

We also have a dedicated support forum located here https://mainwp.com/forum/