Handling out of stock products in e-commerce sites is explained below
1. Removing the category page when the products in the category are not available will make the authority of the category void in search engines. In case if you add some products relevant to that category in future, the page will be considered as a new page by search engines and the value of the page has to build again to rank them in Google.
For example : http://www.example.com/tech-accessories/nexus-cases.html in this category page has been deleted. In case if you add some nexus case products to the site you have to add it in a new category and it may take time to gain authority and rank well on search engines.
2. If you determine that there will be no products added to the category any more, you can redirect the category page to a relevant another category to transfer the authority without any wastage.
For example if you decide there will be no more sale of nexus cases and only nexus 5 cases will be available on the site then you can 301 redirect http://www.example/tech-accessories/nexus-cases.html to http://www.example.com/tech-accessories/nexus-5-cases.html which will pass all the authority to the new page.
3. If a category is a seasonal and will have products only for a particular period, then you can remove the link of the particular page from the site and not the page entirely. The temporary products category can be handled as mentioned below.
- Make a 302 temporary redirect(Only if the new products will be added to the category as soon as possible)
- Show out of stock for the products
- You can hide the links on the site as mentioned in the image shown below. Since there are no products more than 10$ the link has been disabled