Problem deleting user by NukiWeb

In order to allow access to a B&B for a single guest, I created two users with the same name using the app, one for manage a Smart Lock and the other for an Opener.
Later on I deleted these two users by the app without any problem.
However in the nuki web these two users are still present and if I try to remove them I get an error.
I try to remove the user and also to delete the related device, both without success.
Can anyone give me some suggestions to deal with this problem?

This Nuki support answer solved the problem:
Can you please try to synchronize the Nuki Web account? It should solve the problem.
To do so, choose the Smart Lock in Nuki Web. Here , click on “update now” (in yellow, on top of your screen).