DBFinder, One way is to open up the Journal. This lists all the Tasks that have executed. Remove the entry and all its related rows are removed from the ToolsDB. You can remove them one at a time by Right Clicking on the item and selecting Remove. Or you can remove multiple consecutive rows by Left Click and Hold the button while you drag it down (or up) the list to highlight them and then Right click / Remove them.
PS You can also use the Menu item Selected->Remove instead of Right Clicking.