Accepting an applicant means you want to have a Meet & Greet with them.
A Meet & Greet is the opportunity to do a full tour Property Safety Check, Check for Compatibility with the Sitter and their household & pets to see how everyone gets along, to discuss care routines, the Sitters schedule, and expectations and whether the Sitter feels they can meet them with their existing schedule.
If you didn't feel like it was a good match with the Sitter, their pets, other guest pets, other household members, or property, that's okay.
Just let them know by messaging them through the PetCloud app, and then Meet with one of the other Sitters who applied ASAP. Don't delay Meet & Greets, because the sooner you meet, the sooner you will find out if a Sitter and their property is going to be a good match or not. Doing this as early as possible allows you time to meet with another potentially more compatible Sitter.