Hi Ruchi,
I had gone thru will all comments written to you, I agree with most of them but none of them has guided you what framework you should do before initiating any disciplinary action against her.
- Have you issued a copy of Letter of Appointment with relavent clauses for reporting.
- Have you issued and got a copy of Job Description signed by her.
- Do you have certified standing Orders / code of conduct.
- Have you counselled her in presence of her skip level manager.
- Start issuing her memo / notice for any disobedience.
- Do her appraisal as per appointment clause.
After this above ground work now start Gandhigiri.
Do not assign any work to her for seven days make her sit idol outside her workstation. Make her realise that without you Co. is running smoothly assign her work to some one subordinate. Don't forget to invite her for Lunch in cafeteria during Lunch make some remarkable comments like "Jiska Namak Khate hain Uske sath Namak Halali karni chayiye"
Hope she will be on track and will realise her mistake, but even then if she continues you start disciplinary actions with show cause notice folllowing with suspension orders and conduct enquiry before her final termination.
Regards,.....Krishnavat75:-P