Cannot delete a static DHCP lease

The web UI is reporting "The submitted security token is invalid or already expired!".
I think this is a bug as this is happening even after reboots.

The command line

uci delete dhcp.@host[1]

is uneffective as no deletion takes place.
Any hint?

Is the rpcd process running?

Forgot uci commit & /etc/init.d/dnsmasq restart ?

Why should I bother whether rpcd was running?
I didn't stopped it (nor I started it): every other web UI configuration has gone OK so far.

I did uci commit but failed the restart.
But, anyway, a reboot should be more than a restart, shouldn't it?

Because you reported a bug and asked for help.

Your original message did not claim that you rebooted after the uci delete.

I think I actually mentioned it.
Anyway, I opened a bug to the LuCI team some time ago because of this message
"The submitted security token is invalid or already expired!".
I think there could be some problems with LuCI when UCI is not in an expected state, like mine.

Finally, I fixed my configuration by command line, but LuCI is still giving me the token error.
That is:

uci del dhcp.@host[-1]
uci del dhcp.@host[-1]
uci commit # just in case
uci add dhcp host
uci set dhcp.@host[-1].name=myhostname
uci set dhcp.@host[-1].ip=192.168.192.168
uci set dhcp.@host[-1].mac=de:ad:be:ef:d0:d2
uci commit