Before the actual uninstalling you have to reset the page layouts to default. As long as the layouts are still in use Salesforce will not uninstall the app. To reset the layouts to default undo the configuration steps for the layout you did. Also check that you removed CleverReach Permission Set from all users. Then continue with the actual uninstallation:
Go to Setup | Applications | Installed Packages
At the bottom of the uninstall page you must choose if you want to be able to temporarily download your data: „Save a copy of the data for this package for 48 hours after the uninstallation". Alternatively you can delete the data immediately: „Do not save a copy of the data from this package after uninstallation". You will then need to check: „Yes, I want to uninstall this package and permanently delete all its components". Then click uninstall
If there are no further conflicts, you'll receive an email when the uninstallation is complete. Otherwise you are shown what's stopping the uninstalling, after correcting it you just have to reload this page.