...
Uninstall the existing ZT exec agent service using the script UninstallExecAgentServiceWin64.bat . Run files UninstallZebraTesterServiceWin64.bat and UninstallZebraATSServiceWin64.bat in case you also have the controller and ATS services GUI/Controller installed.
Then go to the ZT installation folder and run the Change ZebraTester Installation exe file under the folder _ZebraTester_installation , this will uninstall the existing ZT version.
Restart is not a must after the uninstallation , but if you don't do restart please wait for a couple of seconds so that the uninstallation will clean up all the files , that have been copied as the part of the existing installation. Uninstallation won't delete any files that application created , for example .prxdat files or any config .dat files.
Now please start installing the new 64bit ZT exe or msi package.
After the installation is finished , install the services using the files installExecAgentServiceWin64.bat , InstallZebraTesterServiceWin64.bat and InstallZebraATSServiceWin64.bat ( only need installExecAgentServiceWin64.bat in case of agent server)