Is it possible to conjugate an adjective to its causative form? For example: 気味悪い、おいしい、etc. Is 気味悪いをさせる (make me creep out/ creeping me out) and 美味しいをさせる (make it delicious) grammatically correct?
In most cases, you can use
ku-form + する:
Please make it cheaper.
the spice that makes your dish delicious
Let's make the story more interesting.
However 気味悪い and other i-adjectives related to emotion are a little tricky because they usually have two meanings. 気味悪くさせる usually means "to make it creepy" rather than "to make someone creep out". To say the latter, you can add がる and say 気味悪がらせる.
I made him (look/sound) scary (e.g., using a Halloween costume).
I made him scared. = I scared him.
I made him (look/sound) creepy.
I made him creep out.
When an i-adjective has a verb version, you should prefer the verb version to make a causative-form. For example 悲しい is "sad" and 悲しむ is "to grieve". Technically you can say 悲しがらせる, but we usually simply say 悲しませる ("to make someone feel sad", "to grieve someone").
(Well, after all, "You made me creep out!" is "気味悪い!" or "ぞっとした!", and "You scared me!" is "怖い!" or "怖かった!". Something literal like "あなたは私を怖がらせた!" sounds verbose and funny in Japanese.)