Step 1 - Visit https://www.apollo.io/privacy-policy/remove and complete the opt-out form in the picture below by entering your email and clicking "Click here to opt out of Apollo."  Apollo will use your email to search for any information they have on you and send you an email verification. 

Step 2- Apollo.io should send you an email verification like the one below. You will want to click the hyperlink in the email to proceed with the verification to finalize the opt-out. 

Step 3 - Within 5 minutes of completing the second step, you should receive an email confirming that they have removed your information from their offering. Even if they did not find any records for you in their offering, Apollo must keep an index of opt-outs to ensure this information isn't exposed in the future as they get new data feeds in.  In the data industry, this is called an opt-out table. 

Other resources 

• Free scan to see how much of your personal information is exposed by data brokers and people search networks with one search -  Databroker Exposure Scan.
• Apollo.io - Privacy Policy