Unistall a storagenode

How to unistall a node created with the msi installer?

Why uninstall? OS change?

no, my node got disqualified and i decided to give up

Oh. To bad.
Uninstall msi and delete node folders

based on what did you decide that the node was disqualified? I would not assume that is the case unless it has been confirmed in a support ticket. The node being offline does not mean it is disqualified.