Use APKPure App
Get Contact Blocker old version APK for Android
Let's you block people in your contact list.
Contact Blocker lets you manage what contacts you want to block all in one place. Just hold on a contact and it toggles the block status. When the status changes a vibration is run letting you know that the status have changed and that you can release your finger.
NOTE! This app only changes the contact to go to voicemail. It doesn't stop sms messages!