removing contacts from phone

[apple2android]

My phone contacts were imported / synced by AT&T from a online account with all my phone and email contacts. Every email address and phone number I ever used was imported. How do I remove some of the contacts from my phone? Can I remove them from my phone or do I need to remove them online somehow? When attempting to remove them directly from my phone, I get a an error message " You cannot delete contacts from read only accounrs, but you can hide them in your contacts lists." Any suggestions would be appreacited. Thanks in advance!