Is there a process of declogging the blocked artery without operation?

No. Angioplasty is the non invasive treatment but still this is a procedure that requires intervention. There is no reliable non interventional means to open an artery when it is blocked. The best advice is to decrease the level if risk factors if you have any.
Yes. If by "surgery" you mean an open operation in which an incision is made, the answer may be yes. Balloon angioplasty, stenting, and thrombolysis are options in certain situations. Best to consult with an expert in the field.