My question involves name change laws in the State of: Illinois

I currently use a legal last name of something like 'Lincoln-Smith'. This is due to when I was a child my birth father died, and my step father's last name was added to mine. All my government documents (passports, green card, drivers license, etc), all use the Linoln-Smith name. Throughout my school career i used just 'Smith' as my last name, and continue to do so in my work career. I recently got married and would like to go back to my birth fathers last name for work purposes, bank accounts, etc. I am under the opinion i can switch to that name without going through a full legal name change, as i do NOT want to remove a name from my current last name ('Lincoln-Smith'), but would rather go by the last name of just 'Lincoln'.

Is this possible? Please let me know what, if anything I have to do.

Cheers