Editing an Existing Feature

Go to Edit tab and Press Edit button. ArcGIS Pro edit section bar will become active. 

Select the feature that is needed to be edited. 

Click on Modify Features. 

Select the Edit Vertices Option.  

The vertices of the polygon will become editable. 

You can move the existing vertices, add new vertices, or remove vertices as needed.

You can also utilize the available editing tools such as Reshape Feature, Cut Polygon, Rotate, and Sketch Properties to make the desired changes to the feature.