The QualysContainerSensor.tar.xz file (which you download for sensor installation from Qualys Cloud Platform) has the script uninstallsensor.sh for uninstalling the sensor.
If the docker host is configured to communicate over docker.sock, use the following command:
./uninstallsensor.sh -s
If the docker host is configured to communicate over TCP socket then provide the address on which docker daemon is configured to listen:
./uninstallsensor.sh DockerHost=<<IPv4 address or FQDN>:<Port#>> -s
./uninstallsensor.sh DockerHost=10.11.12.13:1234 -s
Follow the on-screen prompts to uninstall the sensor. Qualys recommends not to clear the persistent storage.