How do I bypass amending the federal to only amend the state for the unemployment tax credit on turbo tax?

You must click on the amendment  option then click on the state tab and choose to amend it.   

it depends on the state. some states start with federal adjusted gross income so you have to go through the federal to amend the state - there is no line for exempt UC on the state amended return is already there by started the amended column with the revised federal AGI.   when going to file make sure in this situation you select mail for federal.  some states do not allow e-filing amended returns.

for other states you can bypass the federal and change just the state