Lincolnshire Fire and Rescue Service said it made the decision after receiving negative feedback about the mascot, which is based on the popular children's TV show.
Now the force's other mascots - fire extinguisher-shaped Freddy, Filbert and Penelope - will be used in place of Fireman Sam.
Lincolnshire's Chief Fire Officer, Les Britzman, said the mascot was "outdated" and did not help sell the fire safety message.
He said: "Firefighters nationally and residents locally have raised some concerns that Fireman Sam doesn't reflect the fire service today, in terms of both the job itself and our workforce.
"It's important to us that our open days and community events don't make anyone feel excluded and therefore we took this decision. We always make sure that we include plenty of activities and other ways to engage children and adults, to help them learn more about fire safety and a firefighter's role."
The mascot has been used by the force in the past to advertise open days, as well as at various charity events.
However, the decision has been heavily criticised on social media.
One Twitter user said: "This increasing desire to remove men from being role models is getting ridiculous."
Another added: "They've really axed Fireman Sam for being a male? This is the world our children are growing up in! Being male is now a problem?"
However, London Fire Brigade supported the decision and wrote on Twitter: "The use of the outdated term Fireman ingrains especially in the young that it is a male only role.
"We've been called firefighters for 30 years and just ask everyone to call us our job title. And that will stop excluding our women firefighters & encourage more to join."
Earlier this year, the service criticised children's TV show Fireman Sam and Peppa Pig of being sexist for using the term "fireman" instead of "firefighter" during an episode.