To start with, you should never "erase" or delete an inbox!  The "inbox" folder is necessary for your application to work properly

Now, I suspect that what you really want to do is to empty all the messages from the inbox.  Depending on the application you are using, you may be able to delete the entire contents of the inbox by right clicking on the "Inbox" label in the files list.  If the pop up menu includes an "empty" selection, you can simply click on that selection.  Use caution here and make double sure that there are no messages that you might need to reference in the future.

If there is no option to empty the entire inbox, you will need open the inbox and look at the listing of messages.  At the left side of the list should be a column of message selector check boxes, one for each message.  You can simply go down the list checking the box for each message but there may be a shortcut.  Just above the box for the first message in the list there should be another check box and when you check this box it automatically checks the boxes for all messages in the list.

Once all the messages are selected with checks in each box, you can mouse the cursor to the "Edit" selection in the menu bar close to the top of the screen and when the menu drops down, select "Delete" and follow any instructions that pop up.  Alternately, your application may have an "X" delete button that will do the same thing as selecting Delete in the edit menu.

If you have a large number of messages with several pages of listings, you may have to repeat this procedure for each page.

I hope this helps

GK