First, have you had a need to access the premises for reasons that are permissible under the Lease? If so, has the presence of the alarm prohibited you from accessing the premises in accordance with the terms of the lease?
If you have had a permissible reason to access the premises and it has been denied due to the alarm, then you should contact a local real estate attorney to determine what remedies you have.
If you have not needed access, but are concerned that you may require it in the future then you should look at the following:
1) Look at the lease to determine what it says in connection with your right to enter and inspect the premises. If you have the right to enter and inspect, only upon notice, then they likely have not violated that section.
2) Look at the section addressing locks. If the tenant does not have the right to install a lock or to change the lock without your consent, or without providing you with a copy of the lock, then they have probably violated that section.
If neither of those sections seem to address it, then you may not have any recourse until the lease is up. If you think that they clearly do then you can send your tenant a notice, in writing in accordance with the terms of the Lease that they are in default of one or more of the sections above and ask that they provide you with the alarm code.
If they refuse, or if you are unsure about what the lease says then you should hire a local real estate attorney to assist you.Ask a similar question