Removal of Norton com.symantec.mes.systemextension

Check with Symantec Norton LifeLock for app removal instructions.

Various add-on anti-malware vendors will offer a downloadable app removal tool.

This appears to be that tool: https://support.norton.com/sp/en/us/home/current/solutions/kb20080427024142EN

If not, or for additional help: Contact a third-party vendor - Apple Support

You can check to see if you've removed all of the supporting files by downloading and running the shareware app Find Any File to search for any files with the application's or the developer's name in the file name.  For that Norton file you'd do the following search(es): 

1 - Name contains com.symantec.mes.systemextension

Any files that are found can be dragged from the search results window to the Desktop or Trash bin in the Dock for deletion.

FAF can search areas that Spotlight can't like invisible folders, system folders and packages.  

If you get warnings that the file can't be deleted because it is in use or used by another app boot into Safe Mode according to How to use safe mode on your Mac and delete from there.

Note:  if you have a wireless keyboard with rechargeable batteries connect it with its charging cable before booting into Safe Mode.  This makes it act as a wired keyboard as will assure a successful boot into Safe Mode.