in built with agentforce builder the developer name already exists what can i do ?

Hey Lokeswara, 

This happens when an agent with that same Developer Name already exists in your org, usually from a previous attempt at the module. Two ways to fix it: 

1. Go to Setup > Agentforce Agents (or search "Agents" in Quick Find), find the existing agent with that Developer Name, and delete it or rename it 

2. If it's tied to a required component you can't remove, easier to just spin up a fresh Trailhead Playground for this module and start clean 

Reference: