There are a couple of options that can be taken if influencers express that they are uninterested in collaborating with you on a campaign. These options are a way to indicate which influencers not to reach out to for future campaign collaborations since they have previously expressed that they are not interested.
The first option is to create a relationship stage that helps you to indicate which influencers decline to join your campaign. A few examples of relationship stages that can be set on these influencers are "Declined," "Paused," "Uninterested," etc... A relationship stage can be created in the "Relationship Stage" section within an influencers profile.
Another option is to create a tag that can help indicate that these influencers have expressed that they were not interested in joining a campaign. This can be done in the "Tags" section within an influencers profile.