Is it advisable to syringe out my ganglion which is on the left side of my wrist on my left hand. Its now the size of a marble?

Possibly. Aspiration of ganglia is an acceptable treatment especial with cysts on the back of the wrist. Unfortunately the likelihood of the cyst resolving permanently is relatively small. I tell patients that the probability of permanent resolution with one aspiration is about 15%.
No . Ganglions originate from an underlying joint. Like a hernia it connects 2 the joint through a small defect. Aspiration only removes the thick jelly like fluid & it takes a large bore needle 2 flow thru. Doing so does not address the cause & it will usually recur. Surgery gets 2 the capsular opening & closes it & prevent recurrence .