Cannot delete file Antivirus One detects on Time Machine Backup

You see this error message when trying to delete a file Trend Micro Antivirus One detected on the Time Machine Backup:

"The operation can’t be completed because backup items can’t be modified."

Why did this happen?

Trend Micro Antivirus One does not have full permission in deleting files inside the Time Machine Backup.

What should I do next?

Delete the detected file manually:

1. On the scan results, click the Manual Delete button. This will open a new Finder window containing the detected file. Leave this window open.

   

2. On the menu bar, click the Time Machine icon, then select Enter Time Machine.
3. Browse the file name that Antivirus One detected as malicious.
4. Right-click the file, then choose Delete All Backups of [item name].