The barriers, placed over warm air vents at the back of a vacant building in St Vincent Lane, were ripped out after widespread condemnation by the city's council and Glasgow City Mission.
Homeless brothers named as Gerald and Paul told how they had sheltered at the site but were forced out by the barriers.
The structures were removed yesterday morning by a 46-year-old activist called Gary, who did not reveal his full name, from the south side of the city. He said it had been "pretty easy" to dislodge them using a 21mm sprocket.
He posted a picture on Twitter from his account @SniperSouthside, showing the barriers piled up in bins, with the message "this is how Glasgow's citizens react to the homeless spikes".
He said he had been angered by similar spikes in London and had to act when something similar was "on my doorstep".
He and three other activists took action after describing the barriers as horrifying in an anonymous statement.
A spokeswoman for Police Scotland said the force had not received any complaints about the removal of the spikes.
She said: "Police Scotland works with a range of partners to make the city centre a safe environment for everyone.
"This includes securing some areas and structures against unauthorised access, particularly to reduce any risk to safety or to respond to complaints about crime or antisocial behaviour. However, Police Scotland has not received a complaint regarding this matter."
It is not known who put the barriers in place. Earlier in the week, the council sent letters to the owner/occupier of the building while it made efforts to trace them, saying there was a seven- days deadline for their removal.
A council spokesman confirmed it had been told of the latest development but did not know who was responsible.
Graham Steven, of City Mission, said: "We would like to thank the members of the public for yet again standing up for our city's most vulnerable. Their anger and disgust at the spikes have in no doubt encouraged a swift removal."
He urged anyone with concerns about homelessness to contact them or the city council. He added that the charity's chief executive had been in talks with the council about how best to deal with homelessness.
Reverend John Matthews, who chairs the Glasgow Simon Community, a homelessness charity, said it could also offer help and support for employers concerned about their staff and buildings.
He added: "We are also trying to spread the word to the general public that if they were concerned about homelessness, they could phone a free phone number and the Simon Team will follow up urgently, addressing the problem without involving the police."
Its phone number is 0800 027 7466.