In user defined selection list is there a way to remove the value 'Not Specify'

Summary

In user defined selection list is there a way to remove the value 'Not Specify'

Content

Hello, 

We would like to know please if there is an option in selection lists, user defined selection list to remove the value
'Not Specify' which is authomatically added to every list .

See attached file for example .

Thanks ,
Revital