If you have connected a project with an external resource pool and you wish to disconnect the project from the pool there are two steps you will need to take.
While the connection is a single-step process, disconnection is a two-step process. The disconnection should be performed in this order particularly if the tasks have been tracked. Once the project is disconnected from the pool, the resources and tracking will remain in the project file.
Step 1: In the Resource Pool file click on: Resource > Resource Pool > Share Resources > Project name > Break Link.
Step 2: Open the resource pool that was being used by the project. Open the project schedule and click on:
Resource > Share Resources > Use own resources > OK.