MacOS 10.13.6 Can't delete or remove applications
What application are you trying to remove? Have you tried with an uninstaller tool?

For exemple, you can follow this to fully uninstall Office 2011: https://support.office.com/en-us/article/troubleshoot-office-2011-for-mac-issues-by-completely-uninstalling-before-you-reinstall-ba8d8d13-0015-4eea-b60b-7719c2cedd17

Many application has the same type of uninstaller.