You can easily hide the out of stock product from the results of your collection page.
To do so, please follow the next steps:
- Go to you Shopify Admin Store > Apps > Searchly.
- Click on Search Result & Collection Page.
- Click on Product label then click on In-stock label.
- Just remove "Out Of Stock" text from the field under Out Of Stock.
- Click on the Save button.
After that, you won’t see out of stock products on your collection page.