Can I stop a particular airline or hotel from showing up in my portal's search results?

Yes, in most cases you can hide specific airlines or properties so they never reach your customers. Agencies do this for all sorts of ordinary reasons, such as a hotel that has given them repeated service problems, an airline whose ticketing rules they would rather not handle, or a property they already sell on a direct contract and do not want appearing twice at a different rate.

How the block is applied depends on where the results come from. Some supplier connections accept the exclusion at the search stage, so the unwanted option is never returned at all, which is the cleanest outcome and the fastest. Others send back everything they have, and the filtering happens on your side just before the list is drawn, which works equally well for the customer but means the option was fetched and then dropped.

Be aware that a block is only as precise as the reference it is built on. Hiding one hotel is straightforward because it has its own identifier, but hiding an airline can also hide the connecting legs it operates on behalf of another carrier, and a chain wide block may catch properties you did not intend to lose. It is also worth remembering that anything you exclude is revenue you are choosing not to earn, so a broad rule can quietly cost you more than the problem it solves.

Before you set one up, write down exactly what you want gone and why, then run a search you know would normally return it and confirm it has disappeared for your customers and not just for you.