'99 Intrigue 3.5L fuel sensor shows 150%

[oldsolds]

I left the headlights on in my Intrigue and when I came back after a few hours, the battery still had some power but the car wouldn't start. The clock had reset, and the fuel level had jumped past full. Now the battery is fine, but the fuel level is still there. There is a small plastic bit that is holding the fuel line there and not allowing it to drop down to the regular range. How can I open the glass in the dash to fix this?