Spamming on Facebook is very common. Link based spam is most common on Facebook. So a Fan page owner needs to have knowledge and tools to ban spammers. Luckily, Facebook has given us a feature to ban spammers. Be sure to use this feature against member who are spamming the page regularly with irrelevant posts and links.
The following steps with pictures will help you ban such spammers:
Table of Contents
Step 1: Use the Comment Settings To Report Comment
On a comment, click on 3 dots and choose “Find Support or Report Comment”

Step 2: In the Popup Choose Spam Reason and Actions to Be Taken

In this popup, you need to select Spam and you can optionally choose to block the person and hide all his comments too.
Step 3: Once Options are Selected, Send button gets Enabled

Step 4: Blocked People Will Not be Able to Comment Anymore and are Reported Too

Step 5: Once You Click Send, Thanks Page is Shown

I highly recommend you follow above steps when someone spams your Facebook Fan page?