How I can delete the old password wifi

Hello
I changed provider and configured the intenretu over WIFI. I gave him the same SSID as it was entered in the Raspberry pi 3, only changed password. Now when I try to connect to WIFI I still have the error. I’m trying to change the password but it is a error. Where can I get the old SSID and remove it. I want to from the beginning setup a network of wifi

If you need help accessing commandline:
https://osmc.tv/wiki/general/accessing-the-command-line/

As Connmanctl forget or delete WIFI marked *