I gather from your initial post that this is a borrowed bike. Are you sure the owner will not let you remove the pedals? It's not rocket science. Both pedals unscrew counterclockwise and install clockwise. Most have an "R" and an "L" stamped in the end of the threaded portion (axle) so you can't mix them up. You can buy a pedal wrench for $10 that makes it easier to remove and later reinstall the pedal. It's longer and thinner than most 15mm wrenches. You just have to be sure to tighten the pedals well when you reinstall them.
Example seller on eBay:
https://www.ebay.com/itm/Lumintrail-Pedal-Wrench-17-16-15-mm-Double-Sided-Bike-Spanner/142738554295?epid=9031295393&hash=item213be17db7&enc=AQADAAAC4FjVrDbVsZ8oH%2F8PNHtt9VX4%2Fw7FZcmMuqs X8uaFEduV3F7s6hvczd5CTg8pc6qTVsPwreDGonEpps%2BNzYHXhFhkAdsbVu502geW4kyj34S6eRU6erVNCP4%2Fccy9uwlWlVd Vj5843ANCsJlqdJc5UMmZfjAS27FNVeSCzB0S3P%2BBdDG0J%2FouoRv1AyOKrGmitvdWf%2BDqtRLD37asnUt%2FumO6BpvCVJx qDOX8ALAU7kCkVzhmo8QxnOq4Tpf7IcMVdBBsb4LyGcOCrKxbH1%2Fk6LWaCQqLPXBlh4kXGDThFLd386GOWvDYGoSodSmuvfXkP uD1v5c7ECT%2Bonh9jvEv8iG6OvyiGfSrdc2ZsOwk1EdIf%2FHFi3i5akhdNk1FHDgvEnBLDIyrcQbu%2BoLgnXSNNUYI6N36CYl 0TGa%2Buud9JeGh4qKOzStw3%2Ba1oDEjIRRCPSGKsv4bpfV72aM%2Fe4%2BCeHaXMT1AapARiHtH06hfcgXeE2N6xr%2FfXhetK YACeSQMl3lh9NBl0XidSbjQWIi7dZNuVEzALbUO5gJ%2FCM5VU%2FpxYU1%2F9iuf951wfTrBvriYHEUXnlbBdteEoSWrZMJPLZz 3%2BG5GlRyl%2FI7sEUk3J68LG8usytjZYYcKsVn3rd%2BG9QYrSGhAnLqtOePF5lkQZwJt8rN03Mu9RLXmUNCF976Mw6teSj3VJ HAQbS27URiu2qETuTNBsCGXsWQA5ZPGeOlPs%2FvYvVJxCQZ55p4rBQIdjwjuM70x89Ay%2FVEdkEnbRddVFLJkufYvMN3XrNQ%2 BxhtMR2EAeuJz0M9lDdTMjBShWHfApYAmxi1k7DK5%2BiSH0Inn5fx6iW0C%2FME08nGUwQxfOgV3X%2FDIo832Yj0gPnVB88HWP KBOe1uWBVZuCQcykv%2FCYY4yMqbK5RrcY6QugGNTaipoiSvBIZUsISwiScCafbLqXOqGOy7bK1CI7LxOnIWABCXmPWv8xLK4h4a GZtc%3D&checksum=142738554295b81c0e3e8a6f48c3bc489f15c8dfa0a3