The most effective way is try to differentiate them from reality. Like imagine someone screaming at you trying to tell you its that or this and you just similing knowing they're wrong as fuck and are not listening to them not paying attention to thier screaming Thats the method, these are just thoughts not reality. When a thought comes try to be like " yeah ok ok" and then be like now lets focus on reality. In starting its gonna be difficult as hell , you'll have a strong urge telling you to engage but over time( some weeks or a month) the urge will weaken to the point you can just laugh and ignore them. Writing in a notebook that " they are just thoughts due to my ocd inagaging in them is stupid" and paste that page in a wall, when the urge is strong look at that page this will also help somewhat.