I want to ask my girlfriend to take her heels off for a picture
Why don't you want her to wear the heels?
I think she is so much prettier without them
You can tell her that you love her in different shoes and you can always ask her to take them off. But if she likes her heels, you don't have any right to tell her what she should wear.
Hey I just want my girlfriend without heels. I can't believe anyone would not want her in flats.
Well, if you tell her she doesn't have to wear them and if she is more comfortable without wearing them, then she can take them off. However, if she said she prefers wearing high heels, then I think you're in the wrong for making her remove it. So I suggest you just tell her to wear something she's comfortable with.