A common scenario is to select/deselect a row with a select/deselect button or checkbox. This is a simple task using the event-bubbling mechanism in Telerik RadGrid. You just need to add two columns with the respective CommandName attribute:

<Columns>
<rad:GridButtonColumn Text="Select" CommandName="Select"></rad:GridButtonColumn>
<rad:GridButtonColumn Text="Deselect" CommandName="Deselect"></rad:GridButtonColumn>
</Columns>

or configure the checkbox to select/deselect the row in its OnCheckedChanged server.

The selected rows will be held server side in the SelectedItems collection of the RadGrid object. In addition, you can hook the SelectedIndexChanged server event of the grid to detect that item has been selected and perform additional operations if needed.

Further details about the server selection of Telerik RadGrid you can find in the Selecting grid items help chapter:
Selecting grid items