You mentioned physical symptoms of anxiety, are there any other symptoms you have been experiencing and any other concerns ncomitant medications that you are on? Ciplar contains Propranolol which only helps with mild physical symptoms of anxiety.
Next Steps
For a dose of 20mg, there should not be any issue in stopping it directly, however better to half the dose for a week or so before stopping it. Also it is better to consult with a Psychiatrist to rule out any existing or previous anxiety issues that may affect the stopping of Ciplar.