Remove all commas from single line of text field

SharePoint JSON formatting now supports replaceAll operator which you can use to remove all commas from a single line of text.

Example:

{ "$schema": "https://developer.microsoft.com/json-schemas/sp/v2/column-formatting.schema.json", "elmType": "div", "txtContent":"=replaceAll(@currentField, ',', '')" } 

Reference: SharePoint: Replace All Occurrences of Substring in a String using JSON Formatting

You would need to create an SPFx FieldCustomizer

Essentially you then would write

@override public onRenderCell(event: IFieldCustomizerCellEventParameters): void { event.domElement.innerHTML = `<div>${event.fieldValue.replace(/[,\.]/g, "")}</div>`; } 

or whatever modifications you'd want to make.

Json column formmatting not provide operators to remove/replace special character currently:

A workaround is to update the single line text field with CSOM Console Application directly to remove commas, please see the same question in the Technet I have replied yesterday:

Remove all commas from single line of text field