Hi Malarie,
The select button mentioned previously does work, but there is another module that I personally find far easier to use.
Under the Pricing and discount management workspace, if you scroll down on the left side there is a link at the bottom called 'Active trade agreements' (unfortunately not available as a standard menu item.
Here you can see all active pricing (purchase, sales, etc) and sort / filter to the lines you need to correct. Once you've selected them, you can click the 'Edit selected lines' from the ribbon, which will pull them into a journal to then set an end date or make your required adjustments.


Note that if you happen to be on 10.0.31, Microsoft adjusted the filter on this module to only show sales pricing and took away the ability to adjust the filter. Since we also use this regularly for purchase pricing updates, we reported this as a bug and there is a hotfix available that will unlock the filters again.
Hope that helps,
Kirk