No one can take your "ex" off the account for you. No one has access to your account. If you are going to use a different filing status you should start a new account with a new user ID. Do not use an old account that has been used for joint returns if you are going to file married filing separately or HOH. It is too messy and difficult to remove the embedded "spouse stuff" from the account.
However---you say "soon to be ex"----indicating that you are still legally married. If you are still legally married, your filing choices are to file married filing jointly or married filing separately. Filing Single is not an option. If you have lived apart for at least the last six months of 2024 and have had physical custody of the children you might be able to file as Head of Household.