The popular and charismatic Shearing informed chairman Colin Dunstall of his decision to leave the Sussex Division Three club on Monday afternoon.
Shearing, who arrived in the summer after a long and successful spell in charge of Division One side Eastbourne United Association, said: "I tried it, did the best I could, but decided it wasn't for me. There's lots and lots of reasons, but I found it really difficult to function at that level. I just couldn't come to terms with it really."
Hopes were high at the start of the campaign after Shearing persuaded the likes of Scott McDonald, Dave Harris, Dominic Douglas and Dave Carey to drop two divisions and join him at The Polegrove.
But despite taking four points from their opening two matches, things quickly turned sour and they claimed just one point from their subsequent three fixtures.
United have lost both of their home encounters, including Saturday's single goal defeat to Loxwood which left them ninth in the 13-team division.
But Shearing insists results weren't a factor in a repeat of the decision he made back in 1999 when he elected to focus his attention solely on his role as chairman.
He added: "I put a lot of time and a lot of money into it in a very short space of time and I desperately wanted it to work. I've not fallen out with anyone and a lot of it I enjoyed, but it's just not professional enough. On Saturday I had nine fit players and two didn't turn up. I can't work like that and I can't understand that mentality."
Secretary Bill Trivett, who was at the helm when Bexhill last won promotion, will take over the reins after the 11th change of boss (including the club's previous guise of Bexhill Town) in just 61 months at The Polegrove.
His first assignment is a Hastings & District FA Intermediate Cup second round tie away to East Sussex Division One outfit Firehills Seniors on pitch one at the Bulverhythe Recreation Ground tomorrow (Saturday). Kick-off is at 1.30pm.
Little Common's marvellous run of form in Sussex Division Three will be put to the test tomorrow when they visit second-placed Newhaven on the back of three successive league wins which have taken them into the top four.
Joint manager Mark Linch said: "That's going to be the big test and the biggest game we've played so far this season." Chas Lister is unavailable and Andy Linch is still out through work commitments.