All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
First of all, we praise Allah Who guided you to Islam and we ask Him to make us and you firm upon faith until we meet Him.
As for the clothes on which there are pictures, then there are some details that you should know about the images themselves.
If the images are of inanimate objects, then there is nothing wrong with them and they are not among the forbidden images.
However, if it is an image of a living being, then it is either a complete image; in which case, it is a forbidden image, and we are ordered in the Sharee’ah to distort it. But if the image is incomplete, such as when the image is of the head only, and the like, then it is not included in the prohibition.
Shaykh Ibn 'Uthaymeen said: “The criterion for the forbidden images is that it must be a complete image as in a Qudsi Hadeeth in which Allah – the Exalted – Said: “And who is more oppressive than the one who attempts to create as I have Created!” Also, the Prophet said about the one who makes an image that, “he will be asked to breathe a soul into it (in the Hereafter), and he will never be able to do so.” This can only be applied when the image is complete. Thus, if one makes an image of the face only, or the hand only, or the leg only, or something like that, then this is not included in the Hadeeth. Even if we presume that it is a complete image, then most scholars are of the view that if the image is despised, then there is nothing wrong with it, such as mats, pillows, and diapers that are in dirty places.” [End of quote]
Based on these details, if the clothes and the items that you intend to donate in charity do not have forbidden images, then there is no harm in donating them. However, if they include forbidden images, then you should take the initiative to obliterate the images and then give the clothes in charity afterwards. If it is difficult to obliterate the images, then we do not see any harm in donating them to non-Muslim poor people as they are not addressed by the branches of the Sharee’ah, according to the view of many scholars.
We advise you, dear sister, to consolidate your relationship with the Book of Allah, and endeavor to seek Islamic knowledge and invite non-Muslims to Islam. The Ummah (Muslim nation) is in a great need of this. The Prophet said: “Convey on my behalf even if it were only one verse.” [Al-Bukhari]
Allah Says (what means): {Invite to the way of your Lord with wisdom and good instruction, and argue with them in a way that is best. Indeed, your Lord is most knowing of who has strayed from His way, and He is most knowing of who is [rightly] guided.} [Quran 16:125]
Allah praised in His Book those who invite people to Him as He Says (what means): {And who is better in speech than one who invites to Allah and does righteousness and says, "Indeed, I am of the Muslims.} [Quran 41:33]
Especially in our time and age when ignorance has become widespread, knowledge has become rare and the attack on Islam and the Muslims is severe.
Allah knows best.