Disable-SPFeature -Identity "Feature1" -Url "http://sharepointsite" -force
Uninstall-SPFeature -Identity "<Feature Name>" -force
OR
Uninstall-SPFeature -Identity "<Feature ID>" -force
Uninstall-SPSolution -Identity testsolution.wsp
Remove-SPSolution -Identity testsolution.wsp
Add-SPSolution -LiteralPath "C:\Packages\testsolution.wsp"
Install-SPSolution -Identity testsolution.wsp -GACDeployment -CompatibilityLevel {14,15}
