If you have ever synced your keychain with any cloud, then a copy of it is saved on respective cloud in an encrypted format. To delete the file from that particular cloud, first you need to disconnect all the devices connected to that cloud and then just follow these simple steps:
Dropbox: Apps folder-->Enpass folder. Just right click and delete the folder.
iCloud: System settings--> iCloud -> Storage --> Manage Storage--> Enpass Password Manager--> Edit--> Delete All.
Box: Files-->Enpass folder. Just right click and delete the folder.
Google Drive: My Drive ->Enpass folder. Just right click and remove the folder.
OneDrive: Files -> Select Enpass folder--> Delete.