I am not sure how you configured your alerts but you can edit them as detailed below:
Start > All Programs > Solarwinds Orion > System Manager
Alerts > Configure Basic Alerts
Start > All Programs > Solarwinds Orion > Alerting, Reporting and Mapping > Advanced Alert Manager
You should then be able to edit the CPU alert you or one of your colleague configured.
If you are looking for a way to modify the thresholds of the webconsole:
Login as an admin.
Click on Admin > NPM Settings
Edit the CPU Load "High Level" and "Warning Level" settings.