in the status window I have 17 items like this one
File not found:Error: Error: ENOENT: no such file or directory, open '/home/foxmask/.config/joplin-desktop/resources/0f23dd26afef41cc89936a928024839f.png'. Path: /home/foxmask/.config/joplin-desktop/resources/0f23dd26afef41cc89936a928024839f.png
How to purge them ?
Is this could be a cause of unsync tags I already have on mobile but not on desktop ?
There’s no way to purge them at the moment, you’d have to delete them manually from the sync target (eg. delete resources/0f23dd26afef41cc89936a928024839f and 0f23dd26afef41cc89936a928024839f.md).
It wouldn’t be the cause of tags no syncing since if these resources show up in the status screen it means they’ve been dealt with and are skipped during sync, so the two problems are probably unrelated.
i checked the tags are well deleted everywhere finally.
and I don’t know where are the resources on the sync target.
should I drop them from dropbox if I can found them?
Yes you can, that will also delete them from the devices.
On android its complicated to spot them 
I did:
sqlite3 .config/joplin-desktop/database.sqlite
select sync_disabled_reason from sync_items where sync_disabled_reason != '';
and get for exemple
File not found:Error: Error: ENOENT: no such file or directory, open '/home/foxmask/.config/joplin-desktop/resources/0f23dd26afef41cc89936a928024839f.png'. Path: /home/foxmask/.config/joplin-desktop/resources/0f23dd26afef41cc89936a928024839f.png
File not found:Error: Error: ENOENT: no such file or directory, open '/home/foxmask/.config/joplin-desktop/resources/00e2d6253c0c46da9708468b09ebb487.png'. Path: /home/foxmask/.config/joplin-desktop/resources/00e2d6253c0c46da9708468b09ebb487.png
File not found:Error: Error: ENOENT: no such file or directory, open '/home/foxmask/.config/joplin-desktop/resources/883ee51817194fb2a9cc7f3a7e000699.png'. Path: /home/foxmask/.config/joplin-desktop/resources/883ee51817194fb2a9cc7f3a7e000699.png
then with an editor a search replace
File not found:Error: Error: ENOENT: no such file or directory, open
by touch
and drop then end of the line '. Path ....'
then copy paste all touch line
then
sqlite3 .config/joplin-desktop/database.sqlite
delete from sync_items where sync_disabled_reason != '';
then start joplin and sync and all is gone 