Yes, as long as this person hasn't signed yet. With the "Manage" role, you can replace their address in the request – for example, if you made a typing mistake or someone else is supposed to sign – or remove the person altogether. The request continues as normal, and the signatures already provided by the others remain valid.
Anyone who has already signed can no longer be replaced. In this case, you must cancel the request and create a new one. At least one person with the "Manage" role must always remain in the request.