You may be used to logging into an account with a username and password, but your account is a little different on OpenSea.
Your OpenSea account is tied to your wallet. Each wallet you have connected to OpenSea is its own account. It's important to note that OpenSea isn't a wallet provider, so we never take possession of your assets or take custody of your NFTs. Additionally, that means that we can't provide password resets.
In order to reset your password for your wallet, you'll need to contact your wallet provider directly or search for the relevant help guide. As an example, here's MetaMask's help article about resetting your password.
You can, however, edit the email address for your account by going to your profile settings. Learn more about editing your account in our help guide, How do I create an OpenSea account?