This instructional ceramics video shows you how to trim a round bowl. It is much easier of you have a centered pot to begin with. It is also helpful to leave a bit of extra clay in the base so that one can trim more freely. Once the clay is semi-dry, you can begin trimming. After trimming, smooth the trimming marks out using a rubber rib. A touch of water on the rim will re-elevate the rim after trimming your round pot.