On Windows, uninstalling Pro Tools does not touch plugins or sessions at all.
Some stuff to remember:
To uninstall on Windows, Right-click Start and select Apps & Features. In that window on the upper, right under Related settings, click Programs & features and find Pro Tools on that list. Right-click and select Change. If you see an option to uninstall Pro Tools AND HD driver, DO uninstall the HD driver(regardless of what version or hardware you have)
