How can I cancel the library card/membership of a child. I want to do it temporarily because she just doesn’t move out of couch! Reading is good habit that I gave her, but, it has become the means to be on couch even at the expense of school.
There are a few choices to prevent a person borrowing books from library, although as a librarian I cannot recommend canceling child's library card and I have no knowledge of a precedent. Also library must act according to library regulations and there is no mention of restrictions for if a person reads too much. As you say, reading is a good habit!
I presume the child is under 15 years old? First comes to mind that without library's interference maybe you could just simply take the card and keep it to yourself for the time being. In case the child has Taskukirjasto (Pocket Library app) which one can use as a library card, it is a bit trickier. You'll have to unload the app from his/her phone.
Technically, library card can be locked or deleted altogether. I suppose as the guardian you have the right to cancel your child's card either temporarily or permanently. It is after all given with your consent. If you find the first suggestion too difficult I suggest you both go to your nearest library and explain the situation so that the staff can make the necessary changes. Take also your ID's with you.
User regulations. Helmet.fi. http://www.helmet.fi/Preview/en-US