@Sivasanmugam typically your Workflows are in a different location than your program files. So you can install and delete knime software without harming your workflow, just tell the new version where the knime-workspace is located. Update should work smoothly.
If you are on windows you can just download a new knime version as a zip file and extract that somewhere and have two version for some time. Although Workflows created in a new version might not be entirely readable in an old version.
Though it always makes sense to have a backup ready