How to stop workflows in sharepoint UI?

Hi @Samuel González Pérez ,

We don't have to activate anything in order to stop a workflow. You could try to use some PowerShell commands to cancel workflows as a workaround if you can't stop it in UI.

PowerShell:

Add-PSSnapin Microsoft.SharePoint.PowerShell -ErrorAction SilentlyContinue  
   
$web = Get-SPWeb "http://your-sharepoint-site-url"  
   
#Get the List  
$list = $web.Lists["Your-List-Name"]  
   
#Get the specific workflow, Associated with the list  
$WorkFlowToCancel = "your workflow name"  
   
# Iterate through all Items and all Workflows on Items  
foreach ($item in $list.Items)  
{  
   foreach ($wf in $item.Workflows)  
     {  
        #Check for the particular workflow  
        if( ($wf.ParentAssociation.Name -eq $WorkFlowToCancel) -and ($wf.IsCompleted -ne $true) -and($wf.StatusText -ne "Canceled"  ))  
        {  
            write-host "Previous workflow status:"  $wf.InternalState  
            #Cancel Workflow  
            [Microsoft.SharePoint.Workflow.SPWorkflowManager]::CancelWorkflow($wf)       
            write-host "Workflow Cancelled at $($list.title)! "  
        }  
     }  
}  

For Reference: Cancel Workflows in SharePoint using PowerShell
Note: Microsoft is providing this information as a convenience to you. The sites are not controlled by Microsoft. Microsoft cannot make any representations regarding the quality, safety, or suitability of any software or information found there. Please make sure that you completely understand the risk before retrieving any suggestions from the above link.

If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.