Braxton, Please give me a little more information so I can help you. I need the FamilySearch ID of your grandmother to look at her record. There are several Pearl's so I'm not sure which record is hers. Are you shown as living or deceased under her record? Looking forward to hearing from you so we can fix this.
Here are some "Knowledge Articles" in 'FamilySarrch'
A person in Family Tree has the wrong spouse
How do I add a spouse or partner in Family Tree?
BEFORE your "Delete"/"Remove" any, "Couple"; and/or, "Parent-Child", Relationship ...
Make sure that you FIRSTLY add her as a Spouse to your Grandfather.
Then you can worry about "Deleting"/"Removing" her as your Mother.
"Changing" a Spouse ...
I hope this helps.