Coat inside of a 4-quart slow cooker with nonstick spray. Stir together cream cheese, Mexican cheese, sour cream, hot sauce, 4 Tbs. scallions, onion, blue cheese, Worcestershire sauce, and garlic in the bowl of a 4-quart slow cooker until well combined. Fold in chicken.
Cover and cook on low for 1 1/2 hours, stirring halfway through. Transfer to a serving dish and stir to combine. Top with remaining 2 Tbs. scallions. Serve with tortilla chips, carrots, and celery.