How to hide/ show Custom button on opportunity detail page in Salesforce ?

Hi Aman,

You can do this by two ways either by creating a VF Page or by using two different record types.

1. Embedding VF Page in detail page of Opportunity page layout.
2. Showing two different Record Types with different page layouts in this way when your condition satisfies the record type having button in page layout appears and when condition not meet then another record type is set with no button in page layout.

You can do one more thing but that will not hide your button, it just throws an error message if the desired condition doesn't met.

Hope this will help you. Will let you know if find more on this.