We have a lot of content about how to manage information in M365 and how to build good metadata models to ensure the information is correctly stored and secured. However, we have not been writing about what you do when information gets outdated. What do I mean by this you might ask? Well let's take an example from the real world. Telefax was common way of distributing information and documentation not that long ago. This has led to lots of companies having "Document type" as a Managed Metadata column in SharePoint Online with "Telefax" as an option. But what do you do when your organisation is no longer using “Telefax” for communication anymore? Lets have a look at the different options:
The first option is leaving it as is. This solution would not be much of a problem the first time you go with it. The user will have one additional value that is redundant, the issue would come over time when these redundant values start to increase and affecting the user experience.
The second option is deleting the term. This solution is a no-go. This will cause the existing documents values where this term is used to appear invalid.
Third option is deprecating the term. This will make the term unchanged on existing documents but will no longer be available when picking values for new documents.
The final solution is to merge terms. Maybe you want to go way from having terms like: Letter, E-mail and Telefax and instead have correspondence as an option for the users. In this case you can then create a new term with the name “Correspondence” and use the merge option to merge the old terms and transform them into "Correspondence". Note: It may take some time until the value gets updated on all the documents.
Besides the option of deleting the term, all the solutions above are viable it just depends on you and the user's requirements