Hello Mehrshad.
It looks like you are using graduated colors symbology? There are a few ways you can change the range of what you see in the legend in ArcGIS Pro.
To change actual values, on the Symbology pane, on the Classes tab, click the Upper value cells to type new values. Alternatively, you can change the symbol class boundaries by click-dragging the boundary values on the Histogram tab.
To change the wording or formatting of the labels (without changing class boundaries), on the Classes tab, click a cell in the Label column and type a new label.
Optionally, click the More menu and click Show values out of range to add a symbol class for any features that fall outside of your defined range.
See Graduated colors—ArcGIS Pro | ArcGIS Desktop for more information. I hope this helps.
Edie
