It depends on your dialect.

Nah. You sound the t. Plen-tee is how you say it. Good day!

No.. prounounced like "plen" + "tee"

My belief is that in ordinary everyday conversation, the "t" is almost always audible. But it is usually a "flap t," not a "true t." I believe that dictionaries are reliable authorities, so I'm about to check one. I feel quite sure that "plenty" with an audible "t" is the most frequent pronunciation. I will be surprised if "plenny" is listed as an additional pronunciation. American Heritage and Merriam Webster show only one pronunciation, with a "t." Therefore, I believe that "plenny" without a "t" sound is not a normal pronunciation, and that when it is heard, it is the result of slurred or sloppy diction.

It is not silent, but the emphasis is on the first part of the word. So, PLEN-ty.