Hi Kristy,
There is almost 100% of the time a clause in your residents' leases that state they must treat staff in a civil manner and violating that clause (cursing at staff, threatening or engaging in behavior that appears to threaten violence) is grounds for certainly a lease violation, up to an including termination of the lease. Your resident seems to be teetering on mental illness from what you have said. I always send a letter to the resident at the time of the first incident and ask that person to come to the office to discuss the issue. In the letter, you can explain how their behavior is a violation according to the terms of the lease and you would like to understand what you can do to help if there are extenuating circumstances causing a problem. It sounds like childish behavior resulting from staff change - maybe she feels like no one likes her, that she isn't getting enough attention from the staff, etc. After that, yes, you can issue lease violations, formally ban the person from the Office (meaning a police officer will serve her NO TRESPASS papers, require all work orders be performed by 2 team members, etc.
I have found that many of these residents do not handle any kind of change well and everything upsets them, from changing from a paper newsletter to a digital one, changing from having free coffee and cookies in the Clubhouse daily to offering only donuts once a week, to not having as many resident events, down to not having someone not say "Hello" to her in the morning. It happens all the time. Residents who behave this way can escalate, or once you talk with them and they get that first violation, they straighten up for the most part.
If this person is threatening staff, you can pursue an Order of Protection and/or evict immediately should there be actual violence/assault (including if the person spits at you and others.) If the person calms down for the most part and is not accumulating violations, you could non-renew them, but I would be very careful to document every single incident, conversation, interaction, etc. It is exhausting dealing with this nonsense. The worst part is if the person becomes diagnosed with a mental illness - then a whole new battle can ensue. Document, document, document.