Hi you may override the shipping address field in this way:
remove_action('mprm_checkout_additional_information', 'mprm_checkout_delivery_address', 5);
add_action('mprm_checkout_additional_information', 'theme_mprm_checkout_delivery_address', 5);
function theme_mprm_checkout_delivery_address() {
if (mprm_get_option('shipping_address')): ?>
<p id="mprm-address-wrap">
<label for="shipping_address" class="mprm-label">
<?php _e('Shipping address:', 'mp-restaurant-menu'); ?>
<span class="mprm-required-indicator">*</span>
</label>
<input type="text" name="shipping_address" value="" class="medium-text" placeholder="<?php _e('Enter your address.', 'mp-restaurant-menu'); ?>" required/>
</p>
<?php endif;
}