When leaving Norway, you should consider closing your bank account. Some may want to leave their Norwegian bank account open, thinking it will make things easier in case they return. If you return fairly soon this could be a good solution, but it could also cause some serious problems for you.
What could happen?
Banks usually charge you a fee for having an account. The fees to the bank are usually withdrawn automatically from your account (you may also have other automatic transfers from your account like membership fees, insurance payments and so on). Leaving just a small sum of money in your account, may fairly quickly turn into a negative balance. A negative balance will usually cause the bank to demand a high interest rate on what you owe them. And if this is not sorted out quickly, the bank may not want you as a customer anymore and your negative balance and unpaid fees are transferred to a collection agency which has even larger fees and interest rate than the bank. Your credit report may also be affected. As a result leaving your bank account open may be very negative and cause serious problems for you.
Closing your Bank Account
Different banks can have different routines, fees and processing time for your request of closing your account. Contact your bank well in advance to find out how to do this. Remember to inform everyone who may transfer money to you that you are closing this account (and give them information on your new account). Maybe your previous employer discovers some unpaid travel bills, the tax office may return money to you, a friend remembers that he owes you some money etc.
Also cut your cards connected to the old account so you do not accidentally use a debit card and get extra things to sort out with the bank.