Hey Krissyswa22,
It appears that you might want to no longer be in the group chat or receive messages from this known number. Is it an iMessage group chat or SMS/MMS group text? It might be possible to leave the group text depending on which type it is: Leave a group text message on your iPhone, iPad, or iPod touch - Apple Support
If you'd like, you can see how to block phone numbers and email addresses here: Block phone numbers, contacts, and emails on your iPhone, iPad, or iPod touch - Apple Support This article also goes over how to report spam or junk as well:
You can report iMessages that look like spam or junk from the Messages app. If you get an iMessage from someone who's not saved in your Contacts, you'll see a Report Junk link under the message.

Tap Report Junk, then tap Delete and Report Junk. Messages will forward the sender's information and the message to Apple, as well as delete the message from your device. You can't undo deleting a message.
Reporting junk doesn't block the sender from being able to send another message. If you don't want to receive these messages, you need to block the contact.
To report SMS and MMS messages, contact your carrier."
We hope that information helps.
Take care.