phone dropped in a pool
To take out the battery first is you remove the battery cover by sliding it. Then you carefully lift the battery cover away from the bottom of the phone. And you can now remove the battery. For a better understanding on how to remove Samsung Gravity battery, download Samsung Gravity manual located here.
https://www.cellphones.ca/cell-phones/samsung-gravity-t459/
You can find the download link for the user manual on the right hand side of the page.