You can't just sell the house if it has a right of pre-emption (otherwise known as a right of first refusal), because as the owner you are obliged to offer the right of first refusal to the parties who can enjoy that right of sale.
What does pre-emption mean?
If a person, company or the government has the right of pre-emption on your property then these parties are given priority over others who are interested in buying your property. In other words, you are obliged to inform the parties with the right of first refusal about any offer from a potential buyer and to offer your house to them first before dealing with a potential buyer who does not have the right of first refusal.
Difference between a legal and conventional pre-emption right
When the legislator offers a pre-emption right to specific persons or governments, we speak of a legal pre-emption right (e.g. pre-emption rights for governmental institutions for nature conservation, town and country planning, combating unoccupied buildings,...)
If a pre-emption right is agreed between several parties (e.g. a landlord who includes a pre-emption right for the tenant in the lease) then we speak of a conventional pre-emption right.
What steps must you take exactly when selling?
If you receive an offer from a potential buyer, it is best to add a suspensive condition in the compromise that the pre-emptive right will not be used.
Then you can inform the parties who benefit from a pre-emptive right of the offer. Ideally with a registered letter. This way they can indicate whether they wish to buy the property at these conditions/price. The notary is also often called upon to write to the beneficiaries in connection with the offer and then a period is agreed within which the party with pre-emptive rights must indicate whether or not they wish to purchase the property.
Once this period expires, the candidate who does not have the right of pre-emption can purchase the property. In this case, the condition precedent is fulfilled. Suppose that a party with pre-emption still wants to buy the house, then this party has priority over the candidate without pre-emption. If you fail to honour this agreement, the party with the right of first refusal can claim damages or even have the compromise declared null and void.