To delete things in the file system, you normally use a command like "del", which is an alias and points to Remove-Item in PowerShell:
get-command del
You can use del to delete a variety of things:
Delete a variable named "test":
del variable:test
Delete a function named "test":
del function:test
Delete an alias named "test":
del alias:test
Delete a registry key named HKEY_CURRENT_USERTest:
del HKCU:Test
You should remember to use the -force parameter if the item you want to delete is write-protected.