If you have $1,800 on line 30 then you are claiming the Recovery Rebate Credit for the first and second stimulus payment ($1,200 + $600 = $1,800).
Yes, if you do not want to claim someone as a dependent then you can remove them from your return. Please select "My Info" on left and scroll down to dependents. Please see FAQ How to amend a tax return for instructions.
Please be aware, if that person meets the requirements to be your dependent then he/she will have to select that they can be claimed as a dependent on their return even if you decide to not claim him/her.
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