If the instrument is not copyrighted, technically, you would not have to get permission to modify or use it. However, it would be common courtesy to seek permission and input from the original author. I would even go the extra mile of asking the original author to review my revised instrument and the methodology I was planning to use.

Good day Sir, whom can i ask permission for.me.to adapt the research instrument.. please recommend here so.that i can email the author direct about my study in Cyberbullying Management and Prevention : A school Program