Jenkins Server uninstallation:
- Go to Add / Remove programs and remove Jenkins (Major.MinorVersion).
Jenkins Slave uninstallation:
- Login to the machine where Jenkins Slave is installled and run “sc delete jenkinsslave-D__Software_jenkinsslave” from command prompt to delete the Jenkins Slave service.
- Restart the machine and verify that the Jenkins Slave Windows Service is deleted.
- Delete D:\Software\jenkinsslave on the Jenkins Slave machine.
Refer here for Jenkins - Installation & Configuration.