To Uninstall it. This worked for me:  
Hello everyone, We are an IT-consulting firm operating with client workstations scattered across the state of Florida. All of the workstations came pre-installed with Dell SupportAssist. With the recent discovery of a vulnerability found in versions prior to 3.2.0.90, we are trying to get every client workstation on the latest, updated version. We are trying to do this without intruding on the end-users' productivity during working hours. Is there a script we can run within command prompt to force Dell SupportAssist to silently update to 3.2.0.90 in the background? Our goal is to perform this update without the end-user being interrupted by prompts of any sort. Thank you in advance to anyone who can provide assistance.
Silently Update SupportAssist in background?