If you find that the Debug menu is a little irritating when trying to use it with 1Password since by default they share the same keyboard shortcut ( ⌘+/ ) , you can go with one of the two options
For 2, Open up your favorite terminal and type in the below command. Use '0' to disable the menu and '1' to enable it. Restart Safari after you are done.
defaults write com.apple.Safari IncludeDebugMenu 0
The above did not work, the below command worked.
defaults write com.apple.Safari IncludeInternalDebugMenu 0
Source: Mac World