That is not 100% correct, "removing" a link (in this case the link to this forum) from a device and selling the smartphone does not solve any problem, if any.
Some ISPs are required (by law) to store their customers' data for between 90 days and 3 years (in some countries 5 years), although logically these policies can vary from country to country, but it must be taken into account that in Canada there are around 250 internet service providers, ISPs legally based in that country must be governed by the same laws, while ISPs legally based in another country but operating in Canada may be governed by other laws. This data is name, IPs and other cookie-based information.