Posted this a while ago to a similar query:
Nope, never been relegated.
But......in the days of the Lancashire Combination and early years of the Northern Premier League, finishing top and bottom did not automatically mean that you were promoted or relegated. During the 1980-81 season we finished 21st out of 22 clubs, level on points with Tamworth finishing above them on goal difference. Due to our poor position we had to seek re-election to the league, which was granted.
In fact, we were crap all the way through the 70's and early 80's not once finishing in the top-half of the Northern Premier. I wasn't alive at the time, but it's all in Potted Shrimp a book charting the history of Morecambe FC by Ken Ormrod. Worth getting hold of a copy if you can.
SV Thread: Have we ever been relegated?, St Albans Shrimp