Wrong Credit Note by unknown supplier against my GST

No you cannot .
Yes but put mail in this regard to your local GST department & In GST portal send message to that supplier under "Communication to taxpayer" . the tab can find under "Services" > select User Services.

keep all hard copies for above communication , will help you in any future litigation.

There is communication portal available on GST, contact with suppliers through their GSTIN and ask them to correct details.

Yes sir ,I've already communicated the same via "communication to taxpayer " tab on portal ,also contacted them on phone and mail still no action by them .

Mam, I've already communicated the same via "communication to taxpayer " tab on portal ,also contacted them on phone and mail , still they are not removing it .

No worry, your communication is a proof that it is fault of supplier and not yours. Keep print out of communication as evidence for future reference.

A supplier raised irrelevant credit note against me which has reduced my ITC Available at the portal, Can I claim the ITC ignoring the credit note for the period, or should I take ITC only whats showing me at the portal?

I have sent the message to the supplier through gst communication to taxpayer.