Contributions in a pull request are verified by an automated build. The checks fail if something is wrong, like to logo is too large or an Ethereum contract is not in checksum format. Checks the exact error message in the build to find out the problem.
A merge conflict happens if the same file has been modified in the pull request, and also in the master branch since the fork was created. With assets repo, this typically caused by using a fork that was created long ago. The simplest solution in this case is to delete your pull request, delete your fork, create a new fork, and create a new PR. Alternatively, a merge conflict can be resolved using git command line, but Git skills are required. A pull request can also happen when overriding an existing logo.
After PR was merged, it may take some time, but not longer than one hour, until search will show the new logo.
Both clients, Android and iOS keep old image cache for up to a few days. In order to see changes immediately, reinstall Trust Wallet. But as always, make sure you have a backup of all your wallets.
A process of removing smart contract information such as (token logo and info) from this repository. Removed contract address will be added to the denylist and, as a result, will no longer be present in token search results inside the TW app. Why would you want to do this ?. You are contract owner or just good samaritan who noticed contract to be no longer "active" and was an upgrade and abandoned by owning organization, involved in a scam, mimicking by its name or/and symbol a real contract. All facts must be supported with a link to any resource proving these statements.