Thank you for your time I asked also in a facebook group and got this answer that worked.
ProjectFolder>ProjectName>Saved>Config>Windows>EditorPerProjectUserSettings Search for “SuppressableDialogs” Should find DeleteVariableInUse_Warning=True change it to false
Make sure project is closed for changes to take affect
I also noticed that if a variable is in use from an other blueprint there is no warning I don’t know if it would be possible to make a warning there or if this “issue” is mentioned before.
Solution credits : FayzedNZ (In this forums)