No delete option for highlighter or underlining.

When this are comments added with Acrobat Reader you can delete the comments. Look at the help of Acrobat Reader.

Unless you have a subscription of Adobe Acrobat Pro DC, I am not sure how this is related to Adobe Acrobat Pro DC, the full desktop computer version, which is not the same as the Acrobat Reader mobile app for Android mobile devices.

This is the support forum for Acrobat Pro DC, do you have a current paid subscription of Adobe Acrobat Pro DC?

If you do, there are premium editing features that will be unlocked in the mobile app only when you sign in with your AdobeID.

Are you saying that you're not able to find these features in the mobile app even if you're signed in?

Also, some PDFs have password restrictions that prevent editing. 

Please confirm if thatis the case or, if you can, would you mind sharing  the PDF that you're trying to troubleshoot?