Some other religions teach God is everywhere. This is actually called pantheism and it is the opposite of our belief system in Islam. Allah tells us clearly there is nothing, anywhere in the universe like Him similar to his likeness, nor is He ever in His creation.
He tells us in the Quran He created the universe in six yawm (periods of time) and then He astawah ‘ala al Arsh (rose up, above His Throne). He is there (above His Throne) and will remain there until the End Times.
Allah has such complete Knowledge as to be able to Know all things past, present and future in all places at exactly the same time. The same can be said for His absolute Hearing and Seeing. In this way, His Knowledge, His Hearing, His Sight is everywhere simultaneously.
In this regard, the prophet Muhammad, peace be upon him, told us He is as close to us as our jugular vein. He also explained Allah is with us when we are in sincere worship to Him and in times of need. Naturally, this would not compromise His existence outside of His creation.
The Quran offers us a more detailed understanding of Where (and Who) Allah is.
Certainly your Lord is Allah, Who created the heavens and the earth in six yaum (days or periods of time), and then He Istawa (rose above) His Throne. He brings the night as a cover over the day rapidly, and the sun, the moon, the stars subject to His Command. Surely, His is the Creation and the Commandment. Blessed be Allah, the Lord of the universe!
[Holy Quran 7:54]
Indeed, your Lord is Allah, Who created the heavens and the earth in six yaum (days or periods of time), and then He Istawa (rose above), His Throne, disposing the affair of everything. No intercessor (can plead with Him) except by His Permission. This is Allah, your Lord, so worship Him. Won’t you then remember?
[Holy Quran 10:3]