A written agreement must be signed. You could, however, have an oral agreement which may be binding. You don't provide any facts so it is impossible to know if you have such an agreement.
As a general rule, unless you had an agreement that provided that the members cannot withdraw, you are free to withdraw on notice,
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The unsigned operating agreement is not binding on you, but that does not mean you are not a member of the LLC. Lots of LLCs have no signed operating agreements. You need to consult a North Carolina business attorney to find out what the default rules are for North Carolina, how you go about dissociating, and what the penalties (if any) might be for doing so.
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