The email application should include an option to mark the messages as spam.
For phonecalls and SMS texts, the phone should include an option to block the phone number.
You could notify the FCC about the offending spammer, too.
Don’t bother trying to unsubscribe. It leaks the same information as above, plus you may get infected. They won’t stop spamming.
Train yourself and your spam filter to catch spam. Never engage.
Also the way email lists work, you may get removed from one, but still end up on a different distribution list from the same organization so you can remove yourself but still get them.
I also don't see anything about actual malware, you are just receiving undesired solicitation. Without the error from the antivirus, there is no telling why it's suggesting you leave. It could be serving something, it could also not be using a valid cert.