To create an alias go to My Site > Pages.
Click on the Page that you want to create an Alias for.
Go to +New > Alias.
Fill in the details and click OK.
Sometimes it can be difficult to find you Alias pages if you have a larger website with a lot of pages. This is how you can use an Advanced Search to find them easily.
Go to My Site > Pages > List View.
Click Advanced Search.
Select Alias from the Module drop-down.
This is how you can delete an Alias.
Go to My Site > Pages.
Select the Alias that you want to delete.
Right Click the Alias and Click Delete...