First open the Settings on your PC and click on the Accounts button shown in this screenshot.
Next, click on the 'Access work or school' button on the sidebar on the left side of the screen. You should see an option to disconnect from the EGCC email address. Click on the Disconnect button and follow the prompts.
After that completes and it is no longer listed here, open a new browser window and attempt to sign into the Student Portal at www.egcc.edu using your student email address and password.