How to removed a footer 'powered By" from a widget plug-in

i was able to hide the yotoptestiminalreview from the page with thise code from my footer.php

<?php if ( is_page(6020)) { ?>
	<style type="text/css">
		#yotpoTestimonialsWriteReview {display: none;}
	</style>
<?php  }  ?>

<?php if ( is_page('submit-review')) { /* ?>
	<style type="text/css">
		#yotpoTestimonials .yoMain, #yotpo-testimonials-custom-tab .yoMain {display: none;}
		.yotpo .yoTop, .yotpo-testimonails .yoTop {display: none;}
	</style>
<?php */ }  ?>

But i don’t know how to removed it from the widget -sidebar