You can remove sorting by specific columns except for sorting by the columns the records are grouped by. These sorting levels can be cancelled by ungrouping records.
To remove sorting:
Right-click anywhere in the grid and choose Customize View from the pop-up menu, then open the Sorting tab of the Customize View window.
In the Sort by These Fields pane, click the field corresponding to the sorting level to remove
and click Remove. Repeat this step for each sorting level you want to remove.