It's my one and only negative with Sonar is that it is not a true wave editor (like you can do in Cubase). The work around is to use "Tool" menu and if your have Wave Lab, Audacity or Sound forge installed they will show on the tool list.
You highlight the track , go to tools, click on Wave Lab, and the track will open in the other software for proper , easy editing.
When finished Save in wave lab and return to Sonar which will ask if you wish to save the changes made click "yes"
I find this works for 80% of my work, but the 20% that it doesn't then involves a big PITA.