Generally, there is no need to close a fund account opened online, unless you don't want to use it anymore. You need to enter a password when logging in, as long as the password is kept well, there is no problem.

And even if someone steals your account, you need to use the bank card registered at the time of opening an account to turn over the funds. The bank card is at your side. As long as you keep it well, there is nothing others can do.

A fund account opened online cannot be closed online. You must go to the location of the corresponding fund company and branch, and I can go there with my ID card in person before going through the relevant procedures for closing the account. See if it is a very troublesome thing, so it is best not to close the fund account opened online unless it is absolutely necessary.

Personal opinion, for reference only.