In short, no.
Once a product has been on the market, the GTIN allocated to it should remain allocated to it, regardless of whether it’s still available to purchase or not. It should never be allocated to another item.
This is because, if a number has been used to identify two different things, there is the danger that the wrong information may be retrieved from a database or online, potentially leading to significant confusion or worse.
Of course, if you have not shared the GTIN and product data outside your organisation, then you are free to change it.
For full details of GTIN non reuse, see Section 4 of the General Specifications