You can delete a sticker pack from your App Drawer the same way you delete apps from your Home screen. Just lightly hold your finger over the sticker pack icon until it begins to wiggle, then tap the little x to remove it from your iOS device. This will remove the sticker pack and main app from both your App Drawer and Home screen. Here's how to hide a sticker pack from your App Drawer:
- Open your Messages app.
- Tap the App Store icon.
- Tap the four dots in the bottom panel.
- Tap the large blue + icon.
- Tap Manage, then tap the slider next to the sticker pack you want to hide/remove.
This will remove the sticker pack from your App Drawer while allowing you to keep the main app on your Home screen.
You can to learn how to delete an individual sticker from a message thread by clicking here.