Answered by Sayyidi Habib Umar bin Hafiz (may Allah protect him and benefit us by him)
What can I recite to remove anxiety and to attain a state of complete trust in Allah?
You should recite the Qur’an and reflect upon it, and repeat verses such as:
هُوَ اللهُ الَّذي لا إِلهَ إِلا هو عَالِمُ الغَيْبِ والشَّهادَةِ هُوَ الرَّحْمَنُ الرَّحِيم
HuAllahu’lladhi la ilaha illa hu, ‘Alimu’l ghaybi wash-shahadah, Hu arrahmanu’ rahim
He is Allah, there is no god other than Him, knower of the unseen and the seen, He is the All-Compassionate, the All-Merciful. (Al-Hashr, 59:22)
You should also repeat the following dhikr:
اللهُ مَعِيْ، اللهُ شَاهِدِيْ، اللهُ حَاضِرِيْ، اللهُ قَرِيْبٌ مِنِّيْ، اللهُ نَاظِرٌ إلَيَّ
Allahu ma’i, Allahu shahidi, Allahu hadiri, Allahu qaribun minni, Allah nazirun ilayya
Allah is with me, Allah witnesses me, Allah is present with me, Allah is near me, Allah watches me.