"Static IP" is too vague. If you mean PUBLIC Static IP, that is either set on your router, or set by your ISP. Since I don't know your router I can't guide you. If it's your ISP you need to contact them.
If you mean LOCAL Static IP (local to your computer), first you need administrative privileges. If you do not have administrative privileges you will never be able to change this.
Assuming you do have network privileges, follow these steps:
1) Start Menu, type in "view network connections", go to the corresponding link
2) Right click on the adaptor you want to change the IP for (I'm going to assume you know how to determine which one you want to change), go to properties.
3) In the list, locate "Internet Protocol Version 4", click on it to highlight it, and hit properties. Double clicking works too.
4) In the General tab:
a) If there are values in the fields, AND "use the following IP address" is selected, clear out the values, do the same for DNS just below. Then switch the IP and DNS to obtain automatically.
b) If there are values in the fields, AND "use the following IP address" is NOT selected, select use the following address, clear out the fields, do the same for DNS, switch both back to automatic.
5) Switch to the "Alternate Configuration" tab. If it is set to automatic, and nothing is in the fields, you're good. If there are values set, make sure user configured is set, clear them out, then switch back to automatic.
6) Click OK to save settings, then OK again. Your network card should now be trying to acquire an IP address through DHCP. Give it a few minutes.
If this does not resolve it, you have a deeper static setting, which requires much further troubleshooting.