Use EICAR test strings as passwords so when the password is stored as plain text the antivirus software will delete the file.

Sadly it wouldn’t work if found in a CSV file with other records:

According to EICAR’s specification the antivirus detects the test file only if it starts with the 68-byte test string and is not more than 128 bytes long. As a result, antiviruses are not expected to raise an alarm on some other document containing the test string