How to refresh a thumbnail in social networks

Sometimes when publishing a tour on social networks like Facebook, Twitter or LinkedIn the thumbnail shown is not the one that we currently have defined in VT PRO. These social networks have their own cache so if we published the link before we may need to refresh the cache so it takes the more recent thumbnail. Here is how:

https://support.shareaholic.com/hc/en-us/articles/360000263426-How-to-Clear-Link-Preview-Cache-Stored-by-Facebook-Pinterest-LinkedIn-Twitter