Well, firstly, I'll just make it clear that Mods/Admins don't delete accounts at the request of members. So, your only option would be to delete all the information on your account and just not return under the same name, assuming of course that you still want to leave. If not, fantastic. :super_hap
But I will offer to you some advise of my own because I am in a very similar situation to you. I work for an insurance based company in Britain and I am one of the board members. As such, I am also seen as a 'representative' of this company and any action I take, inside or outside of work, can be harmful to the company. As such, revealing my identity on a forum such as this could harbour harsh consequences... especially taking into consideration the fact that I am also a staff member. So like you, I fear being sacked from my job. I know the whole idea sounds silly to others (and I can truly understand why they think that) but it's the reality of the situation. Shareholders don't want to mess around with a company where one of its board members has interests elsewhere. It looks unprofessional.
Anyway, even though these things can happen, it doesn't necessarily mean that it will. Just be careful with what you reveal online. I've revealed nothing about myself bar my name, and I plan to keep it that way. So if your careful about what you write on here, I see no real reason for you to leave.