No, you do not need to sell your house with an agent. FSBO (for sale by owner) is a common way to sell property. However you will not receive the benefits of being listed in the MLS. In addition, without “quality data” you may not choose the correct sales price (value).
You can post it on websites like Zillow, FSBO and others, but exposure is limited. Potential buyers may also be looking for a discount since you are not paying a real estate commission.